A doomsday scenario that global fisheries face collapse is simplistic and for many species plain wrong, according to a new study from researchers with the Pelagic Fisheries Research Program at the University of Hawai'i.

Many fisheries are being too heavily harvested, but management agencies are taking steps to protect them, researchers said.

The fisheries scientists were responding to a paper published Nov. 3 in the journal Science that suggested that overfishing is leading toward marine ecosystem collapse, and that by 2048, all the current international fisheries could be gone.

"Marine biodiversity loss is increasingly impairing the ocean's capacity to provide food, maintain water quality and recover from perturbations," wrote a scientific team — led by Boris Worm of Nova Scotia's Dalhousie University — in a paper that got media play worldwide.

"I was in Australia and watched it on Australian TV as it broke. It set off a panic," said Stephanie Fried, senior scientist with Environmental Defense.

But fisheries agencies and independent fishery researchers were quick to reject the conclusions as alarmist and unsupported by current fisheries data.

According to Pelagic Fisheries Research Program researchers, a number of major fisheries — including Pacific fisheries for yellowfin and bigeye tuna — are being harvested sustainably.

Their report, "Biomass, Size and Trophic Status of Top Level Predators in the Pacific Ocean," was scheduled to be published in the journal Science today.

Authors of the report are program director John Sibert, John Hampton of the Secretariat of the Pacific Community, Mark Maunder of the Inter-American Tropical Tuna Commission and NOAA Fisheries scientist Pierre Kleiber.

"Management of ocean ecosystems in the 21st century will require comprehensive analysis and not the half-baked approaches used in some recent papers and so widely reported in media," Sibert said in a statement.

The Nov. 3 report has been criticized for making assumptions about the health of fish stocks from limited data — primarily catch results — which Sibert said is not sufficient to make determinations about the size of the remaining stock.

The authors of the new report said they studied all available data for tuna fishing in the Pacific from 1950 to 2004 and used the information to create estimates of the impact of fishing on those species.

They conclude that some fisheries are being appropriately managed, but that further management is needed when conditions change.

In the case of yellowfin and bigeye tuna, there is a threat from growing international fishing fleets that are increasing the pressure on the species, they said.

The Western Pacific Regional Fishery Management Council has made recommendations to limit the harvest of these tunas, and those recommendations are now being reviewed by NOAA, said Marcia Hamilton, an economist with the fishery council.

Hamilton said that researchers have concluded that while they are not technically overfished, there is overfishing of Pacific-wide stocks of bigeye and the western and central Pacific stocks of yellowfin. The regulations are being prepared to prevent those species from becoming overfished, she said.

Fried with the Environmental Defense said she is wary of the fishery industry's statements about the condition of fish stocks. She said there is evidence that many international fishing fleets may far understate their actual catch, and the impacts of overfishing are showing up in fish markets around the world.

"In many parts of the world, fish catch has diminished. People are selling what used to be considered trash fish" because preferred fish are in short supply, she said.

Reach Jan TenBruggencate at jant@honoluluadvertiser.com.